Functionalized organozinc reagents can easily under 1, 4-addition reaction withunsaturated esters in the presence of catalytic amount of Ni (acac)_2 and tertiary ammes under verymild conditions to give the products in...Functionalized organozinc reagents can easily under 1, 4-addition reaction withunsaturated esters in the presence of catalytic amount of Ni (acac)_2 and tertiary ammes under verymild conditions to give the products in excellent yields.展开更多
A novel CF_3-containing building block, (Z)-ethyl 3-bromo-4,4,4-trifluoro-2-butenoate, was easily prepared from CF_3CBr_3, the former reacted with alkynes Or organozinc reagents in the presence of Pd complexes to affo...A novel CF_3-containing building block, (Z)-ethyl 3-bromo-4,4,4-trifluoro-2-butenoate, was easily prepared from CF_3CBr_3, the former reacted with alkynes Or organozinc reagents in the presence of Pd complexes to afford useful CF_3-containing intermediates in good yield.展开更多
Functionalized organozinc reagents can easily conduct 1,4-addition reaction with unsaturated esters in the presence of Cu(OAc)2 and LiCl under very Anld conditions to give the products in excellent yields.
Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromi...Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.展开更多
In this paper the C--F bond activation of polyfluoroaryl imines is explored at cobalt（0） center with an imine-N atom as an anchoring group. The reaction of F5C6-CH=N-（2＇-ClC6H4） （2） and FsC6-CH=N-C6H5 （3） wit...In this paper the C--F bond activation of polyfluoroaryl imines is explored at cobalt（0） center with an imine-N atom as an anchoring group. The reaction of F5C6-CH=N-（2＇-ClC6H4） （2） and FsC6-CH=N-C6H5 （3） with Co（PMe3h afforded the C-F bond activation products （ortho-F4C6-CH=N-（2＇-CIC6H4））Co（I）（PMe3）3 （5） and （ortho-F4C6-CH=N-C6Hs）Co（II）（F）（PMe3）2 （6）, while only n-（C=N） coordinated cobalt（0） complex （2,4,5- F3C6H2-CH=N-（4＇-ClC6H4））Co（0）（PMe3）3 （4） was obtained from 2,4,5-F3C6H2-CH=N-（4＇-C1C6H4） （1） without C--F bond activation. Complexes 4--6 were characterized through X-ray single crystal diffraction. It was also found that dialkylation of N-（perfluorobenzylidene）benzenamine with organozinc reagents could be catalyzed by Co（PMe3）4 via C,C-coupling reaction under mild conditions.展开更多
文摘Functionalized organozinc reagents can easily under 1, 4-addition reaction withunsaturated esters in the presence of catalytic amount of Ni (acac)_2 and tertiary ammes under verymild conditions to give the products in excellent yields.
基金This work was partially supported by the National Natural Science Foundation of China.
文摘A novel CF_3-containing building block, (Z)-ethyl 3-bromo-4,4,4-trifluoro-2-butenoate, was easily prepared from CF_3CBr_3, the former reacted with alkynes Or organozinc reagents in the presence of Pd complexes to afford useful CF_3-containing intermediates in good yield.
文摘Functionalized organozinc reagents can easily conduct 1,4-addition reaction with unsaturated esters in the presence of Cu(OAc)2 and LiCl under very Anld conditions to give the products in excellent yields.
文摘Some Stemona alkaloids belonging to the tuberostemospironine group possess a spirolactone moiety with anti-configuration （C-9/C-9a）. In this paper, we describe two approaches to this structural unity. By using bromine atom as a traceless directing group, the SmI2-mediated reductive coupling of ketone 6 and fl-bromomethacrylate proceeded with complete anti-diastereoselectivity. In the absence of an a-directing （chelation） group, the one-pot reaction of the ketone derived from alcohol 15 with the organozinc reagent generated from bromomethacrylate af- forded spiro-a-methylene-y-lactone derivative 16 as a single diastereomer. These two highly diastereoselective methods would find application in the synthesis of stemona alkaloids containing anti-configured spiro-lactone/pyr- rolidine moieties. In addition, on the basis of our previous work, the total synthesis of （-）-9-epi-11-demethyl- sessilifoliamide J （11）, and an improved synthesis of （-）-9,11-di-epi-sessilifoliamide J （9） were accomplished.
基金Acknowledgement We gratefully acknowledge the support by National Natural Science Foundation of China （No. 21172132）. We also thank the kind assistance from Prof. Dieter Fenske and Dr. Olaf Fuhr （Karlsruhe Nano-Micro Facility, KNMF） for the X-ray diffraction analysis.
文摘In this paper the C--F bond activation of polyfluoroaryl imines is explored at cobalt（0） center with an imine-N atom as an anchoring group. The reaction of F5C6-CH=N-（2＇-ClC6H4） （2） and FsC6-CH=N-C6H5 （3） with Co（PMe3h afforded the C-F bond activation products （ortho-F4C6-CH=N-（2＇-CIC6H4））Co（I）（PMe3）3 （5） and （ortho-F4C6-CH=N-C6Hs）Co（II）（F）（PMe3）2 （6）, while only n-（C=N） coordinated cobalt（0） complex （2,4,5- F3C6H2-CH=N-（4＇-ClC6H4））Co（0）（PMe3）3 （4） was obtained from 2,4,5-F3C6H2-CH=N-（4＇-C1C6H4） （1） without C--F bond activation. Complexes 4--6 were characterized through X-ray single crystal diffraction. It was also found that dialkylation of N-（perfluorobenzylidene）benzenamine with organozinc reagents could be catalyzed by Co（PMe3）4 via C,C-coupling reaction under mild conditions.
